namespace Helion.Util.RandomGenerators;

/// <summary>
/// Uses the Doom RNG table.
/// </summary>
public class DoomRandom : IRandom
{
    private static readonly int[] Random =
    {
        0, 8, 109, 220, 222, 241, 149, 107, 75, 248, 254, 140, 16, 66, 74,
        21, 211, 47, 80, 242, 154, 27, 205, 128, 161, 89, 77, 36, 95, 110,
        85, 48, 212, 140, 211, 249, 22, 79, 200, 50, 28, 188, 52, 140, 202,
        120, 68, 145, 62, 70, 184, 190, 91, 197, 152, 224, 149, 104, 25,
        178, 252, 182, 202, 182, 141, 197, 4, 81, 181, 242, 145, 42, 39,
        227, 156, 198, 225, 193, 219, 93, 122, 175, 249, 0, 175, 143, 70,
        239, 46, 246, 163, 53, 163, 109, 168, 135, 2, 235, 25, 92, 20, 145,
        138, 77, 69, 166, 78, 176, 173, 212, 166, 113, 94, 161, 41, 50,
        239, 49, 111, 164, 70, 60, 2, 37, 171, 75, 136, 156, 11, 56, 42,
        146, 138, 229, 73, 146, 77, 61, 98, 196, 135, 106, 63, 197, 195,
        86, 96, 203, 113, 101, 170, 247, 181, 113, 80, 250, 108, 7, 255,
        237, 129, 226, 79, 107, 112, 166, 103, 241, 24, 223, 239, 120, 198,
        58, 60, 82, 128, 3, 184, 66, 143, 224, 145, 224, 81, 206, 163, 45,
        63, 90, 168, 114, 59, 33, 159, 95, 28, 139, 123, 98, 125, 196, 15,
        70, 194, 253, 54, 14, 109, 226, 71, 17, 161, 93, 186, 87, 244, 138,
        20, 52, 123, 251, 26, 36, 17, 46, 52, 231, 232, 76, 31, 221, 84,
        37, 216, 165, 212, 106, 197, 242, 98, 43, 39, 175, 254, 145, 190,
        84, 118, 222, 187, 136, 120, 163, 236, 249
    };

    private int m_randomIndex;

    public DoomRandom(int index = 0)
    {
        m_randomIndex = index;
    }

    public int NextByte()
    {
        m_randomIndex = ++m_randomIndex & 0xFF;
        return Random[m_randomIndex];
    }

    public int NextDiff()
    {
        m_randomIndex = ++m_randomIndex & 0xFF;
        int value1 = Random[m_randomIndex];
        m_randomIndex = ++m_randomIndex & 0xFF;
        int value2 = Random[m_randomIndex];
        return value1 - value2;
    }

    public int RandomIndex => m_randomIndex;

    public IRandom Clone() => new DoomRandom();
    public IRandom Clone(int randomIndex) => new DoomRandom(randomIndex);
}
